The present invention relates to a circuit configuration for a vehicular brake system with anti-lock control and/or reaction slip control which is equipped with wheel sensors for generating electric signals representative of the wheel rotational behavoir. Electronic circuits are provided for conditioning, logically combining and processing the sensor signals and for generating braking-pressure and/or starting-torque control signals. Circuits are provided for cornering indentification and for generating signals characcteristic of cornering and for comparing these signals with the vehicle speed.
A circuit configuration for automotive vehicles with traction control of this type is disclosed in German patent specification P 31 27 302. By means of the cornering-identification device described in this patent specification, a signal characteristic of cornering is obtained alone by evaluating the signals supplied by sensors which are arranged at the two wheels of the non-driven axle. In order to augment the driving stability, this cornering signal serves to reduce the starting torque of the vehicle enging during cornering if only one of the drive wheels tends to spin and, simultaneously, a threshold value of the vehicle speed is exceeded. The cornering identification is based solely on the measurement of the difference of the numbers of revolution between the two front wheels. Therefore, a difference between the numbers of revolution which is due to different tread radii of the two wheels, as caused by different tire profiles or tread wear, will result in an error signal, or the threshold of response of the cornering identification will be set to be so high that relatively narrow bends can only be detected which must be cornered with low speed for physical reasons.
Further, a circuit configuration for a slip-controlled brake system is known with a cornering-identification circuit which in each case sums up the slip of the two wheels of one vehicle side and compares it with the sum of slip of the wheels on the other vehicle side (U.S. Pat. No. 4,657,313 issued Apr. 14, 1987 and corresponding to German published patent application P 34 13 738). As soon as the difference of the slip value sums of both vehicle sides exceeds a limit value, the selection criteria will be temporarily changed, for instance from select-low to select-high, and thus the braking pressure variation. This way, the braking pressure variation is conformed to differing conditions when running straight and cornering, to the end that in each situation driving stability and steerability of the vehicle is maintained to the extent possible. Differences between the rotational speeds which are caused by different tread radii also impair the exactness of cornering identification and the evaluation of these signals in this known circuit.